An apartment-dweller in Tver, Russia installed a video camera on his or her front door, looking out into the stairwell, then uploaded a compendium of amusing and/or interesting moments to YouTube. The neighbors seem generally hostile to surveillance, though some of them are in no condition to notice it.
Google Translate suggests the following caption: "Pensioner, hammer and inadequate man camera shot war neighbors in apartment building in Tver."
Tip: use stickers. Legal, easily carried, completely effective, no damages.